Filtering apparatus



Dec. 16, 1941.

D. B. BANKS `2,266,402 FILTERIN'G APPARATUS Filed May 2, 1958 8Sheets-Sheet l 1,07 w 106 409 /9 /04 22 l 27 2/ 23 u ,o o, 2] 26 27 2225 3o /f/f/ Dec. 16,1941. D. B.' BANKS l 2,266,402

FILTERING APPARATUS Filed -May 2, 1938 s sheets-sheet 2 DM. 1.6, 1941. DB BANKS FILTERING APPARATUS Filed May 2, 1958 8 Sheets-Sheet 3 Dec. 16,1941.

naz/0 A 7704 D. B. BANKS FILT'ERING APPARATUS Filed May 2, 1958 8yShee'cs-Sheetl 4 #up al @Am/,ways JA #W5/V701? Y cznfc S Dec. 16, 1941.D. B, BANKS FILTERING APPARATUS Filed May 2, 1958 8 Sheets-Sheet 6Armen/fyi Dec.- 16, 1941. l D,B BANKS ,2,266,402

FILTERING APPARATUS Filed My 2, 1958 i asheepS-sheetf/ 39 f3 U3 .f/ 43 I54 58 f7 I 40 f4? i l 4, .44 l e @11M 47 49 fag '5% /\r j' i l n Fia/2.V -J/3 48 37 $5/ Dec. 16, '1941. D. B. BANKS FILTERING APPARATUS FiledMay 2, 1938 -8 Sheets-Sheet 8 v QS MN Patented Dec. 1e, 1941 Daniel B.Banks, Drexel Hill, Pa.,

Oil Company, Philadelphia, Pa.,

o! New Jersey assigner to Sun a corporation Application May 2, 193s,serial No. 205,566 s claims. (c1. 21o- 200) The present inventionrelates to an apparatus for filtering and particularly to an apparatuswherein a continuous process of ltering and lter cake removal can becarried out.

The dewaxing of hydrocarbon oils is at 'the present time being carriedout by diluting the oil to be dewaxed with a liqud'normally gaseoussolvent-refrigerant such as propane or butane, as these hydrocarbonshave the property at low temperatures of dissolving oil and reducing itsviscosity to a degree permissive of proper filtra-v tion, and also ofbeing relatively pure solvents for the wax crystallized from the oil atlow temperatures. Since the dewaxing operation is carried out atextremely low temperatures, of the order of F. to 70 F., and since thesol- .vents above referred to are extremely volatile and explosive, itis necessary that filtration be carried outentirely within a closedchamber and, due to the large volumes of material which it is necessaryto handle, that the operation be continuous.

'-It is therefore an object of the present invention to provide anapparatus wherein a continuous process of iiltration and lter cakeremoval may be carried out.

It is also an object of the invention to provide an apparatus whereinthe iilter surfaces will be in contact with the ltrand for a period oftime relatively long with respect to the time occupied -by the removalfrom the ltrand of the lter for the purpose of removing the caketherefrom.

It is also an object of the invention to provide adjustable means foraccurately timing the blow back for removing the cake with respect tothe suction time.

It is a further object of the invention to provide sampling vmeansenabling the iiltrate being removed from each of a multiplicityv ofiiltering units to be inspected continuously.

it is a further object of the invention to pro-v vide means for shuttingof! one of a multiplicity of sections of filtering elements withoutdisasf sembling the entire unit.

It is a further object of the invention to insulate and separate theiiltrand from heat conducting relation with the outside shell of theillter in order to prevent excessive evaporation of solvent throughlieat leakage into the flltrand. It will be understood that the termtlltrand, as herein used, has an established meaning in the oil reningart and denes the mixture of oil and wax to be separated. while' theterm l1lltrate" deiines the oil after separation,

The drawings illustrate a preferred embodiment of the invention.

Fig. 1 is a sectional elevation of an apparatus embodying my invention.

Fig. 1A is an enlarged view showing a' portion of the samplingconnections.

Fig. 2 is a section 'taken on Fig. 1.

Fig. 2A is an enlarged detail of a portion of the mechanism fortemporarily stopping, the rotation of the illter elements and removingone section thereof from communication with the outlet.

Fig. 3 is a section taken on line 3 -3 of Fig. 1.l

Fig. 4 is a diagrammatic illustration showing a development of the camused for lifting the filter elements from the iiltrand and showing thepositions of the various valves during the filtering and filter cakeremoval operations.

Fig. 5 is an elevation showing a single lter leaf partly broken away.

Fig. 6 is a partial section taken on line 6-6 vof Fig. 5.

Fig. 7 is a partial -section taken on line 1-1 of Fig. 5.

Fig. 8 is a section taken on line oi Fig. 5. v,

Fig. 9 is a view showing the adjustable cam arrangement for operatingthe blow back valves.

Fig. 10 is a plan view partly in section of the structure shown in Fig.9.

Fig. l1 is a section taken on Fig. 9. y f

Fig. 1,2 is a view, partly in section, showing the valve means withinthe filter leaf supporting arms for alternately connecting the lterleaves with the source of vacuum and blow back.

line ll-II of Fig. 13 is a lsection taken on line |3-l3 of Fig. 12.

Fig. 14 is an elevation partly in section showing the filter leaves andthe arm supporting them.

Fig. 15 is a in Fig.,14.'

-In lordeigthat the detailed description of the present invention may bemore Vclearly underplan view of the structure shown stood, a generaldescription of the apparatus without reference to thevarious figures ornumerals will iirst'be given.

The fllter consists of a vertical cylindripal shell capable ofwithstanding either pressure or vacuum having therein a rotatablecentral shaft carrying a multiplicity of arms which bodily rotate in aiixed plane, and which have mounted thereon lter leaves. The centralshaft at its.

upper end also carries arms-having rollers which lines 2-2 of follow acam track and by means of connections to the filter arms swing thefilter leaves, at predetermined intervals, outv of -contact with thefiltrand. The central` shaft also contains radial supporting means forcarrying the filtrate con,-

trol valves, the blowlback valves, control mecha- .nism therefor andpiping incidental thereto, the

central shaft also serving as ingress means for the blow back sas and asegress means for the filtrate, the shaft and all of thematerialsupported thereby being carried from a .bearing structure at the toppart of the vertical cylinv drical chamber. Two cam mechanisms are em,-ployed, one of which is fixed with relation to an annular troughcarrying the filtrand and cake removal sections and the other of whichis ad- .instable to permit proper and regulableoperation of the blowback valves. The annular trough carrying the flltrand, as well as thechute or fiume through which the wax cake is dropped,

shaft I5 and the element 33. Rigidity is given the structure justdescribed by means of obliquely extending anchor braces 32 boltedtobrackets on the shaft I5. Supported by rods and turn buckles 33 and 33a`(hung fromradial members 23) and a ring .34 welded to the shaft |5is anannular sectional plate 35.? (see also Fig. 2). The structure justidescribed supports the weight of the\ lter elements, valves, andpipingincidental thereto as well as the rods used to control the blow backvalves. l

Each of the filter elements includes a tubular shaft 43 rotatableaxially through an arc of about 92. On an extension (hereinafterdescribed) of each shaft 43- is positioned a set of filter leaves 33;-five comprising a set in the present embodimerit.r At the inner end oftubular shaft 43 is a valve mechanism for alternately connecting theshaftwith a source of vacuum for withdrawing the filtrate and a sourceof gas under pressure for blowing back to remove the cakefrom the filterleaves. 'I'his valve mechanism-consists oi a casting 31 (Figs. 12 and13) having a plate 33 closing one end thereof and a gland 33 pack'- ingthe tubular shaft 43, which is turnable within casting 31. The end oftube 43 is closed4 bya stub Ashaft 4| which is` welded theretol and onwhich the inner race ofa roller bearing structure 42 isV placed, theouter race being set within ing mechanism associated therewith.` Thismech;-

anism is substantially identical with thatl disclosed in Patent No.2,068,257, issued January 19, V1937,1:o the applicant arid Paul D.Barton, the main difference being that means,` hereinafter described,are provided for the admission of blowback gas therethrough.

- Carriedby the bearing member I3,l by means of bolts 23, is a Ilargespur gear I4 which is affixed to the ,central shaft I5. Spurgear |4meshes with a` pinion I3 driven by a shaft -|1, which extends through-anozzle-I3k in the upper portion of the shell and is packed by passingthrough a stumng box I3. Power is supplied to shaft I1 for rotating,through pinion I3 and spur gear I4, the shaft I5 and the mechanismcarried thereby. Immediately below spur gear I4 there are pivotallyconnected to shaft I5, by suitable Aan-'annular ring 43v abutting ashoulder in the casting. Tube 43 and race 42 are held in position bymeans of a nut- 44 on the end of stub shaft 4|. 'j Casting 31 servesfasa valve body .to place the filter leaves in communication with both thesource-of vacuum and the source of blow-back gaseous fluid.Communication with the blow back is through pipe 45. Communication withthe source of vacuum or filtrate outlet is through pipe 43. Tube 43,-isprovided with an orifice 41 for. such communication.` In order toproviders.

tight seal, an internal sleeve 43 is provided whichy is groundto fitlthe internal surface of the valve body 31. This sleeve hasan orifice 43registering meansa multiplicity of radial arms 2| having' rollers 22ailixed at their extremities. Rollers 22 are in engagement with anannular cam 23, which is supported, by suitable structurel members|24and 25; from the outer shell of chamber 3.

By reference to Fig. 4 it will be noted that cam 23 is provided with araised portion, adjacent the blow-back section of the lter, whereby thecam necessarily effects the lifting and lowering of arms 2|, which,through means hereinafter described, lift 'the set of lter leavessuccessively outoi' the flltrand and return them thereto after the cairehas been removed. Arms 2| are guided, in the vertical movement caused bycam 23, by means of guides 23 depending from spur gear I4 and rollers 21carried within an opening l .provided in the arms 2|; rollers 21following guides 23 and rollers 22 following cam 23 being placed onopposite ends of a stub shaft.

- Immediately below arms 2| and cam 23 is a supporting structurecomprising radial members 23 bolted to an annulus 23 welded to the shaftI5. .Aiilxed to the extremities of radial members i 23 is a circularstructural element 33 (Fig. 3).

Another circular structural .element 3| is ailixed -with orifice 41 intube 43. Sleeve 43 is split, as

shown,- at 433 and isJ ordinarily made larger in size than the internalground surface on the valve body 31, so that oninsertion it expands andprovides a tight fit. Positioned on'the tube 43 are two lugs 5I and 52,held in place by suitable screw. These lugs serve to turn the sleeve 43with the tube 43 so that aligning openings 41 and 43 will register withone or the other of the openings leading to pipes 45 and 43, dependingupon the position of the tube 43. It is readily apparent that tube 43may be Ainserted and then sleeve 43, after which, the plug 53 beingremoved, lugs 5I and 52 may be positioned.

Tube 43 is pressed and welded into a casting 54 which has integraltherewith a quadrant 55 (see also Fig. 15) which, when actuated ashereinafter explained, eects the turning of the tube. On theopposite-side of casting 54 a ground andpolished tube 53 is inserted andwelded thereto as shown -at 51. vA sleeve 53, having lugs 53 thereon, isthen slipped over tube 53 andwelded yt0 the casting 54. On tube 55 theheads 3l of to radial members 23 about midway between the 'l5 filterelements 33 are placed. Openings 33 in tube 53 aii'ord communicationbetween the filter elements and tube 53. The outer end of tube 53 isclosed by a plug 34, which is welded therein, the outer end of the plugbeing provided with a screw thread. A gland 35 is placed over the outerend of the tube 56 together with a gasket 35a.. A drilled b0ss35 on theclamp aligns with vperiphery thereof and foraminous ing heat frompassing `tube 58; and when the slotted bosses 62 on the nlter elementsand lug 59 on the ring 58. A key rod 61 is then inserted and the wholestructure tightened by a nut 68 having lug washer 69 between the nut'andclamp 65. There is thus provided one element of the filter, having fiveseparate leaves rigidly connected thereto, rotatable about an angle ofabout 92.

Each nlter element 36 consists of a casting 6| (see Figs. -8) havinggrooves 10 on the outer plates 1| set within a shoulder provided in theouter rim. The filter cloth 200 is stretched over the outer faces of thecasting and is held thereon by forcing the cloth into grooves by meansof a compressible packing such as rope, lead wire or the like. Thefilter cloth is prevented from bulging excessively when the blow-backgas is supplied thereto byy means of spools |10 inserted within thefilter and held in place by collets 12 and bolt iii.4 The casting 6|forming the frame of the filter element is so designed as to provide aconductor pipe it leading substantially to the bottom of the casting,this pipe being connected through the cored opening 15 to the opening 53in the tube 56.

The filter elements 36, when in their lowered position, travel throughan annular trough |60 to which nltrand is furnished through pipe 18(Fig. 1). Trough 50 is supported by means of suitable brackets ISIattached to the lter shell and is insulated therefrom by means of anysuitable insulating material 19, thus preventthrough the metallic shelland brackets into the nltrand. Within the filtrand admission pipe 18 isplaced an insulating expansible joint 80.

As the nitrate passes through the nlter cloth, it falls to the bottom ofthe filter element and nows up, through the conductor pipe 14, into thenlter leaf is rotated through approximately 79, a substantial portion ofthe nitrate therein will drain into the tube 56. The filter elements 35and tubes 56 and 40 are turned about their axes by means of straps orchains 15 secured at their lower ends to the lowermost portions of thequadrants 55 and at their upper end to rods 11 hung from arms 2|.

It is apparent that as the rollers 22 on arms 2| ride up on the inclinedsurfaces of cam 23 (Fig. 4)

as shown in Fig. 2, has four one nlter arm. There are manifold s1which,Y inlets each serving four such manifolds, each of whichcommunithe nlter elements will be swung through ap-- proximately 92 toeffect their removal from the nltrand and their placementin position forthe blow-back. At the samel time the openings in the tubular shaft B0and sleeve i9 are registering with the opening communicating with theblowback gas inlet 45.

At the opposite side of the shell from the filtrand inlet 18 is placed awax nume 8|. This nume extends down through the annular trough |60 (seealso Fig. 4) which is cut oif from communication therewith by transversewalls 82. The wax nume is elongated in the region of the top of thetrough |60 and tapers down to a square shape immediately below thetrough, from which itmerges into a circular piece 89 extending within anozzle 8l in the wall of the outer casing. The flange on the lower endof the nozzle 84, extending outside the casing, isbolted or otherwiseamxed to means for transporting the wax either to storage or to a meansfor further treating the same.

The nitrate, after passing through the valves 31 at the ends of thenlter arms, flows down through pipes 46, having valves 86 therein, to aoil to, and

cates withl the central shaft and is bolted or otherwise affixed to acasting 88 which in turn is affixed to the shaft I5, thus making itnecessary to yprovide only four openings 09 in the shaft I5 andconsequently not greatly reducing its strength.

Immediately below the openings 89 there is welded, inside the shaft I5,an annular hood 90, the purpose of which will be hereinafter explained.Fromthe lowermost position of each of the pipes 46 a horizontal pipe 9|extends through the shaft I5 and, at a particular point in its rotation,passes over a stationary vertical pipe 92 within shaft I5 and a nozzle93 at the lower portion of the outside wall of the vessel. Pipe 92communicates through line 94 with a gauge glass 95 positioned outsidethe nozzle 93. From the lower end of the gauge glass 95 a line 96extends into a ntting on the lower end of the nozzle 98. passes overpipe 92 about midway of the filtration portion of the cycle, pipe 46will be quite well nlled with nitrate, a little of which will pass outthrough line 9| instead of through manifolds ,81.

As the outlet end of pipe 9| passes over pipe 92, nitrate will passthereinto and thence down and into the gauge glass, thus permittingl theoperator to ascertain whether or not there is any wax suspended in thenitrate, which fact would indicate that the cloth had become ruptured orthat some other break or leak had occurred prmitting unfiltered materialto enter the filtering.

the pipe 92, as the annular shield extends below the upper end of thepipe 92.

The pipes 45 furnishing the blow back gas to the nlter elements extendupward to valve mechanism 91, the operation of which is controlledl byrods 98. A nange on each valve casing (see Fig. 3) is bolted to a nangedpipe which communicates with a. manifold 99, which in turn communicateswith the central shaft I5 through a line |00. Operation of each of thevalves 91 is carried out by means of a lever |0I positioned on top ofthe valve and operated by partial rotation of the corresponding rod 98.

Since there are sixteen blow back valves, each of which communicateswith a manifold serving four valves, it is necessary to provide onlyfour openings in the upper end of the shaft I5, thus not greatlyreducing its strength. Below the openings |02 communicating withmanifolds 99 there is welded a diaphragm |03 that completely seals theupper portion of the shaft I5 from the lower portion. Further up in theshaft i5 there having a line |05 connected thereto and openingtherethrough. Line |05 extends through the cover |06 of the nlter,through a packed joint, to a ntting |01, to which is connected a line|08 furnishing the blow-back gas.

In the upper portion of the filter there is also provided lines |09 and||0 which serve to admit allow it to flow from, the bearing structuresupporting the nlter mechanism.

The outer end of each rod 98 operating a blow back valve 91 is providedwith a lever III (see Fig. 9) having a roller ||2 on the end thereof.Lever III is free to rotate about rod 98, but its Since the dischargeend of pipe 9| rotation relative thereto is restricted by means of setscrews in projections I I3 on a collar ||4 xed on rod 98.

Positioned about the wax chute al, and arl ranged so as to contact therollers II2, is an adjustable cam composed of parts II5 and II6. Theouter side of the entry side of the cam II 5 is provided with markings I40 to facilitate setting of the apparatus. For instance, if a valve 91is to begin opening when the corresponding wheel I|2 is in the positionshown in Fig. 9, the upper set screw is turned down to just the pointwhere it contacts with a lug I4| on lever III. The lock nut is thentightened. The lower set screw is then fixed to limit the fall of thearm III when the wheel I|2 passes toward the end of the cam .I I6 inorder that it will not fall below the level of the entry side of cam|I5. As the roller rides up cam I|5 beyond the position shown in Fig. 9,shaft 98 is turned to open the corresponding blow-back valve.

Cams I|5 and II6 are pivoted at II1 on a support |22 and, by means ofbolts ||8 and IIS, engaging with the nut |20, are held within a fork |2Ion the end of a bracket secured to support |22 (see Fig. 11).

Bolts 8 and IIS are provided with opposite threads so that properadjustment may be made. The support |22 for the cams II5 and ||6 isslidably mounted upon a. track |23 secured to the shell I and is held inplace by bolts |26 passing through slots |24 in a strip |25 secured tothe shell I0. The general position of the cams II and II6 with respectto the chute 8| may be thereby suitably adjusted. Bolts I 21 extend,through slots |28 in plate |22, into threaded holes in Vcams II 5 andI|6, thereby providing means for clamping these cams in any desiredposition and limiting the movement thereof.

It is apparent from the foregoing that the operation of the valves 91can be very closely controlled to bring about proper blow backconditions, proper adjustment being extremely necessary with varyingspeeds of the lter. It is well known that filter rates fall on rapidlyas the filter cake grows n thickness. Therefore, if filter rates arehigh the apparatus must be speeded up to prevent too thick a cakeaccumulating, thus cutting down yields. From consideration of Fig. 4 andfrom the description of the operation of the valves 31, it will beapparent that the time when the vacuum valve begins to close and thetime it is fully closed are xed, regardless of the speed of revolution,by means of the fixed cam 23. The times, however, for beginning to openthe blow-back valve, the time during which it is fully open, and thetime for closing it, may be very carefully controlled by propermanipulation of cams ||5 and II6. v

If inspection of gauge glass 35 shows that the stream being pulled fromone lter section is cloudy, thus indicating a leak or filterclothrupture, thatV particular section may be cut olf from communicationwith the filtrate outlet by operation of valve 86. As shown in Figs. 1and 2, there is provided a shaft |30 having a forked end |3| extendinginto the filter shell adjacent ,the line of travel of the hand wheels onthe valves 88. The shaft |30 passes through the shell through a nozzle|32 having suitable packing associated therewith lto prevent gas leakingfrom the shell. The shaft terminates in a hand wheel |33. By referenceto Fig. 2A, it will be noted that the outer end of the shaft |30 islarger in diameter than the inner portion. Where the larger diameterconverges to the smaller diameter, a cam face is formed which isutilized to operate switch |34 which is diagrammatically illustrated inFig. 2A. In order to cut olf a filter arm from communication with thefiltrate outlet, the rotation is watched until the valve 86 controllingthat portion which it is desired to eliminate from the system comesopposite the shaft 30, at which time the main switch controlling thedriving motor is cut oil', thus stopping rotation of the shaft I5.Handwheel I 33 is then pushed, opening switch |34 which is connected inseries with the main switch, thus preventing the starting of the motor.Further inward movement of the handwheel I 33 engages fork 3| with thespokes of the handwheel on valve 86, permitting it to be turned to aclosed position, after which operation shaft |30 is withdrawn, closingthe switch |34 and permitting rotation to be resumed when the mainswitch is again closed.

A fluid level of ltrand is maintained in the annular trough |60 by meansnot shown, which means will control an inlet valve situated in line 18.

The lower end of shaft I5 is provided with a flange and wear sleeve |35which is machined to t closely within an annular member |36 fastened tothe outer shell I0. Suitable packing means to prevent leakage of gas orliquid, such as packing |38, are held in place by gland I 33.

The filter structureherein shown is easily assembled. The shaft I5,having wear sleeve |35 aixed thereto, is lowered through the top of themanhole and set within the bearing |36 aflixed to the bottom of thecasing I0. The spur gear I4, which is made up in sections which readilypass through manhole |50, is then assembled in its proper position. Theelement I3, together with the bearings associated therewith, is thenlowered through the manhole ||3 and the bolts 20 are put in position anddrawn up lifting the shaft I5 from the shoulder provided by the bottomof the bearing |36. The spur gear I4 and the shaft I 5 will then besuspended entirely from element I3 and the bearings associatedtherewith. The arms 2| and guides 21 are next assembled, it beingunderstood that the cam 23 and its supports 24 and 25 are already inplace, after which the radial arms 28 and their associated structuralelements are put in place. The lower manifolds 81, together with thevalves and flttings associated therewith, are next put in position andthe plate 35 is assembled above them, upon which the shafts 40, valves31, valves 31 and the necessary piping and fittings are installed. Thefilter leaves 36 are then placed upon the shafts 40 and the mechanismadjusted for operation.

From the foregoing description, the operation of the apparatus will beunderstood. The shaft I5 and the mechanism carried thereby are rotatedand the mixture of oil-propane solution and wax is pumped through theline 18 into the trough |60. The filtrate from the filter sections thatare immersed in the mixture flows continuously through the correspondingtubular shafts 56 and 40, pipes 86, manifolds 81 and the lowersection ofshaft I5 and thence to a locus of further treatment for separation ofthe propane them and the tubular lthe manifolds 99, into pipe the filterand as a means shafts with the corresponding blow-back gas pipes I5. Atthe points in its travel, predetermined stationary cams H and H6, atwhich a rollercarrying lever lll riding on a cam H5 turns thecorresponding rod 98 on its axis to open the corresponding valve 91,blow-back gas is admitted under pressure through pipes |08 and |05, theupper section of shafts I5 and, through one of 45, tubular shafts 40 and56, and thence into the corresponding lter section 3E, blowing the cakeof wax thereon into the wax discharge chute 8l. Soon thereafter, as theroller-carrying lever rides down cam H6 and turns the corresponding rodt8 to close valve 91, the flow of blow-back gas is shut oi. after whichthe corresponding arm 2i, riding` down to the lowsection of cam 23,turns the corresponding tubular shafts 56 and l@ and filter section 3eback into the trough EEO, thus again immersing it in the flltrand,whereupon its filtering function, and the flow of nitrate therefromthrough tubular shafts 56 and to, the corresponding pipe et and thelower section of shaft is, are resumed. I

Inspection of the bv-passed filtrate that iiows through the glass gauget5 enables theoperator to determine if and when any particular ltersection is not functioning properly and, by the described manualoperation of shaft i313, the rotation of the apparatus can be stopped,the de fective filter section cut out by closing the corresponding valvei3@ and the apparatus restarted.

an important feature of the described apparatus is .that the movingparts are all supported from a central shaft, which in turn is supportedfrom a single bearing structure,- the central shaft being used as ameans for removing nitrate from for admitting blowback gas thereto. Itis also evident that the arrangement Afor rotating the filter leaves tolift them from the iiltrand, carry them over the wax removal section andplacethem again in the nltrand is one which is perfectly balanced andwhich requires only straight vertical motion. It will be noted, byconsideration of Fig. 4, that each time one of the wheels 22 is ridingup on the cam track 23 to remove one set of leaves from the filter,another wheel 22 will be traveling down the opposite end of the camtrack, thus balancing the apparatus.

It will also be observed that it is only necessary to support the weightof the iilter leaves by the lifting cam 23, as the leaf-carryingelements 56 and Mi are entirely supported from the structure 28.

The maximum amount for the leaves to remain within the leaf structureand the means for removing and again depositing the leaves in thenltrand are so arranged as to have the leaf in contact of time ispermitted by the adjustment of the ltrand, as

with the ltrand practically up to the time it is removedl for thepurpose of removing the accumulated wax cake. It is evident from Fig. 4that in a structure as here shown having sixteen lter sections,three-quarters, or twelve of the sections, will be in the itrand whileonly onequarter, or the remaining four, are either in the process ofremoval from or in the process of returning to, the filtrand. It willreadily be appreciated, comparing the present structure with the usualtype of rotary, nlters,M that a filter embodying my invention possessesa much greater ,eiiiciency horizontal leaf or drum Patent is:

1. A filtering apparatus comprising an enclosing shell, an uprightrotatable central shaft, an arcuate flltrand trough within the shell, anumber of radiating tubular shafts rotatable bodily with the centralshaft above said trough, a wax discharge, a filter carried by, andcommunicating with the interior of, each tubularshaft, a filtratedischarge and a blow-back gas pipe for each tubular shaft, means to turneach tubular shaft on its axis into two positionsin one of which itswings its filter into the trough and in the other of which it swingsits filter out of the trough, valve means operable in the nrst of saidpositions to connect said tubular shaft with its lter discharge andvoperable in the other of said positions to connect said tubular shaftwith its blow-back pipe while it is traveling over the wax discharge,and means operable in the rotation of the central shaft to so actuatethe several tubular shafts successively.

2. A filtering apparatus comprising an enclosing shell, an uprightrotatable central shaft, an arcuate nltrand troughwithin the shell, anumber of radiating tubular shafts rotatable bodily with the centralshaft above said trough, a wax discharge, a nlter carried by, andcommunicating with the interior of, each tubular shaft, a nitratedischarge and a blow-back gas pipe for each tubular shaft, means to turneach tubular shaft on its axis into two 'positions in one `Aof which itswings its lter into the trough and in the other its niter out of th'etrough, valve means operable in the first of said positions to connectsaid tubular shaft with its nlter charge and operable in the other ofsaid positions to connect said tubular shaft with its blow-back pipewhile it is traveling over the wax discharge, a valve in each blow-backpipe, and means operable in the rotation of the central-shafttosuccessively actuate the several tubular shafts as specified and, whilea blow-back pipe and tubular shaft are so connected, operate said valve.

3. A ltering apparatus comprising an enclosing shell, an uprightrotatable central shaft, an arcuate trough for the filtrand within theshell. a series of nlters rotatable with the shaft, means rotatable withthe shaftand connected with th'e lters and adapted during their rotationto move them into and outof the trough, a filtrate discharge, meansoperable in the rotation of the shaft to maintain open communicationbetween each filter and the filtrate discharge while it is travelingthrough the trough, by-pass means adapted to be brought into opencommunication with each of the streams of nitrate flowing from eachfilter during a portionof the time 'that each filter is moving throughsaid trough in order to divert a small portion of said stream ofnitrate, means in said by-pass for visually inspecting said filtrate inorder to detect any defective operation of such filter, and a valveoperable munication between such iilter and the nitrate dischargetothereby render inoperative a defective filter.

4. A iiltering apparatus comprising an enclosiing sh'ell, an uprightrotatable central shaft, an

'carried by and communicating with the interior of each tubular shaft, ablow-back gas pipe and What I claim and desire to protect by Letters altrate discharge pipe for each tubular shaft, means to turn each tubularshaft on its axis into two positions in one of which it swings itsfilter into the trough and in the other of which it swings its lter outof the trough, valve means operable in the first o! said positions toconnect said tubular shaft with its lter discharge and operable in theother of said positions to connect said tubular shaft with its blow-backpipe while it is traveling over the wax discharge, a cam-way extendingwithin members rotating with the shaft and rolling over the cam-way, andconnections between said radial members and the respective tubularshafts adapted to effect the turning of the latter successively on theiraxes as specied.

5. A filtering apparatus comprising an enclosing shell, an uprightrotatable central shaft, an arcuate trough for th'e ltrand within theshell, a series of lters rotatable with the shaft, means rotatable withthe shaft and connected with the iilters and adapted during theirrotation to move them into and out of the trough, a ltrate discharge,means to convey iiltrate from each lter to the ltrate discharge th'roughthe trough, a source of blow-back gas under pressure, a valve adapted toopen connection between said source and each iilter while it.

is out of the trough and thus in non-ltering position, a rod adapted tooperate said valve, said rod and valve being bodily rotatable with thecentral shaft, a roller carrier by said rod, a stationary and around theshell, radial while it is travelingl cam along which said roller isadapted to travel while said filter is out of the trough and by whichthe operation oi said roller and rod is controlled to turn said valvesuccessively into open and closed position, means to adjust said camalong the path of travel of said roller and means to adjust said rollerrelative to said rod to th'ereby control the time of opening and closingof said valve and the length of time during which it remains open.

6. A nltering apparatus comprising an enclosing sh'eli, an uprightrotatable control shaft, operating means for rotating said shaft, anarcuate trough for the iiltrand within the shell, a series of mtersrotatable with the shaft, means rotatable with th'e shaft and connectedwith the lters and adapted during their rotation to move them into andout oi' the trough, iiltrate discharge pipes, with which said ltersrespectively communicate while the lters are traveling in the trough, avalve on each ltrate discharge pipe which is operable to close said pipeand render the corresponding filter inoperative, valve operating meansextending through said shell and operable from the exterior thereof forclosing one of said last named valves, and means actuated by theoperation of said valve operating means for rendering said operatingmeans for rotating said central shaft inoperable during said closure ofsaid valve.

DANIEL B. BANKS.

